A tunnel partly collapsed on Tuesday at a plutonium handling facility at the Hanford Nuclear Reservation in Washington state, leading authorities to evacuate some workers.
Workers took cover and turned off ventilation systems after minor damage was discovered in the wall of a transport tunnel.
The damage was more serious than initially reported, and the take-cover order was expanded to cover the entire facility after response crews found a 400-square-foot section of the decommissioned rail tunnel had collapsed,
Hanford emergency center spokesman said that there was no evidence of radiological release at site.
